What you need to know
- Wall detectors have limits and can give false positives or false negatives.
- Cables and pipes often follow predictable routes, but never rely on assumptions alone.
- If the consequence of a mistake is serious, stop and get professional help.
Use your own measurements
Use the linked BricoDato resource to check these inputs in your own situation. Walls can hide plumbing, electrical cables, metal framing and reinforcement.
Before making a hole
Look at sockets, switches, radiators, taps and service points. Think about the likely path of electrical cables and water pipes before using a detector.
What can confuse a detector
Metal studs, foil-backed insulation, damp materials, reinforcement and uneven surfaces can affect readings. Learn the tool on a known area first.
Use repeated passes
Scan horizontally and vertically and approach the target from several directions. Mark the edges of repeated detections rather than trusting a single beep.
Electricity and plumbing need caution
Isolate circuits where appropriate and never assume a wall is safe because one scan found nothing. Near bathrooms, kitchens and service routes, be especially cautious.
A safer decision process before making a hole
Walls can hide plumbing, electrical cables, metal framing and reinforcement. Domestic detectors help narrow uncertainty but cannot prove that an area is free of services.
Example to adapt
Imagine a shelf bracket positioned above a wall socket. Instead of relying on one scan, inspect both sides of the wall where possible, locate visible fixtures and cable routes, and compare repeated detector passes in different directions. If the detector response is inconsistent, move the bracket or seek qualified help rather than guessing.
| Warning sign | Why it matters | Prudent response |
|---|---|---|
| Socket or switch nearby | Cables may travel within the wall | Avoid drilling until route is established |
| Pipework or radiator below | Hidden pipes may continue vertically | Change location or request assessment |
| Uncertain detector reading | Depth/material can distort results | Treat as inconclusive |
Checks before acting
- Read the detector manual, including depth limits and materials it cannot detect.
- Inspect the other side of the wall and nearby kitchens, bathrooms or electrical points.
- Use a fixing suitable for the verified wall material and expected shelf load.
- Stop if any indication of a cable, pipe or unusual construction remains uncertain.
Final check
A consumer wall scanner can indicate hidden metal, some wiring or changes in density, but its silence cannot prove a place is safe to drill. Scan in two directions, test it over a known target and inspect service routes from nearby sockets, switches and plumbing. The result can change with wall thickness, foil insulation, reinforced concrete or sensor calibration.
- Inspect likely cable and pipe routes.
- Test the detector on a known target.
- Scan in more than one direction.
- Stop if readings are inconsistent or the risk is high.
Keep a small job sheet
Record proposed hole positions, visible fittings, scanner model, readings and chosen safe alternative.
Turn the guide into a decision
Mark the proposed hole positions and wall material, then select fixings compatible with the verified substrate. If any indication remains ambiguous, stop and seek qualified investigation before penetrating the wall; damage to a hidden cable or pipe can be dangerous.